Lighting apparatus

ABSTRACT

The lighting apparatus according to an embodiment includes: a housing including first and second back covers each having an inside surface in a parabola shape; a recess opened at a lower portion of the first and second back covers; a light-transmissive sheet arranged obliquely in a recess of the first and second back covers; a light emitting module between the recesses of the first and second back covers; a heat dissipation body in which the light emitting module is disposed; and a first reflective sheet for reflecting light on an inside surface of the first and second back covers, wherein the heat dissipation body includes a heat dissipation portion in which the first and second light emitting modules are disposed and a reflecting portion disposed between the heat dissipation portion and a lower end portion of the light-transmissive sheet, and the first reflective sheet has a plurality of reflective surfaces.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S. National Stage Application under 35 U.S.C. §371 of PCT Application No. PCT/KR2016/006075, filed Jun. 8, 2016, whichclaims priority to Korean Patent Application No. 10-2015-0081380, filedJun. 9, 2015, whose entire disclosures are hereby incorporated byreference.

TECHNICAL FIELD

An embodiment relates to a lighting apparatus.

BACKGROUND ART

In general, a lighting apparatus using a LED generates a hightemperature when the LED turns on. This heat results in reduction in thelife of a lamp and various components supporting the lamp thereof.

When a lighting apparatus using an LED is used, a problem of hot spotmay occur. The need for lighting structures to reduce such a hotspotproblem and prevent glare is growing.

DISCLOSURE Technical Problem

An embodiment provides a lighting apparatus for a flat panel.

An embodiment provides a lighting apparatus having a light emittingdiode (LED).

An embodiment provides a lighting apparatus for preventing glare.

An embodiment provides a lighting apparatus that reflects opposite sidelight of a plurality of LEDs to a light-transmissive sheet.

An embodiment provides a lighting apparatus that uniformly irradiatesside light emitted from a LED with specular reflection and scatteredreflection to a light-transmissive sheet.

Technical Solution

A lighting apparatus disclosed in an embodiment includes: a housinghaving a first back cover including a recess at lower portion and areflective surface of a parabolic shape; a first light emitting moduledisposed on one side of the recess of the back cover and having aplurality of light emitting diodes (LEDs); a light-transmissive sheetdisposed obliquely with respect to an optical axis vertical to the topsurface of the light emitting diode at a recess of the housing andtransmitting light emitted from the light emitting diode, wherein thereflective surface includes a first reflection region adjacent to theLEDs and a second reflection region disposed between an upper portion ofthe light-transmissive sheet and the first reflection region, whereinthe first reflection region reflects light incident from the LED to adifferent region of the second reflection region, and the secondreflection region reflects irregularly light incident from the firstreflection region to a center region of the light-transmissive sheet.

According to an embodiment, a lighting apparatus includes: a housingincluding first and second back covers disposed on opposite sides of acenter and each having an inside surface in a parabola shape; an recessopened at lower portions of the first and second back covers; a firstlight-transmissive sheet disposed obliquely in a recess of the firstback cover; a second light-transmissive sheet disposed obliquely in arecess of the second back cover; a first light emitting module having aplurality of LEDs inside the recess of the first back cover; a secondlight emitting module having a plurality of LEDs inside the recess ofthe second back cover; a heat dissipation body in which the first andsecond light emitting modules are disposed in a region between therecess of the first back cover and the recess of the second back cover;and a first reflective sheet disposed adjacent to the LED in the insidesurfaces of the first and second back covers, and reflecting first sidelight emitted from the plurality of LEDs, wherein the heat dissipationbody includes a first heat dissipation portion in which the first lightemitting module is disposed, a second heat dissipation portion in whichthe second light emitting module is disposed, a first reflecting portiondisposed between the first heat dissipation portion and a lower end ofthe first light-transmissive sheet, and a second reflecting portiondisposed between the second heat dissipation portion and a lower end ofthe second light-transmissive sheet, wherein the first reflective sheethas a plurality of reflective surfaces.

Advantageous Effects

An embodiment may provide a lighting apparatus for new flat panel.

An embodiment may improve uniformity of light in a lighting apparatusand improve glare.

An embodiment may reflect side light of a plurality of light emittingdiodes (LEDs) and may provide an improving effect of glare on alight-transmissive sheet.

An embodiment may improve reliability of a lighting apparatus.

DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded perspective view of a lighting apparatus accordingto an embodiment.

FIG. 2 is an assembled perspective view of the lighting apparatus ofFIG. 1.

FIG. 3 is a side cross-sectional view of the lighting apparatus of FIG.2.

FIG. 4 is a partial enlarged view of the lighting apparatus of FIG. 2.

FIG. 5 is an exploded perspective view of a heat dissipation body and aheat dissipation cover of FIG. 1.

FIG. 6 is an assembled perspective view of the heat dissipation body andthe heat dissipation cover of FIG. 5.

FIG. 7 is an enlarged view of a first back cover of the lightingapparatus of FIG. 3.

FIG. 8 is a view illustrating first and third reflective sheets on thefirst back cover of FIG. 7.

FIG. 9 is a detailed view of a region of the reflective sheet on thefirst back cover of FIG. 7.

FIGS. 10 to 13 are views illustrating paths of light reflected from thefirst reflective sheet of FIG. 7.

FIGS. 14 to 16 are views illustrating paths of light reflected from thethird reflective sheet of FIG. 7.

FIG. 17 is a side cross-sectional view illustrating a light emittingdiode according to an embodiment.

MODES OF THE INVENTION

Hereinafter, preferred embodiments of a lighting module or a lightingapparatus having a heat dissipation structure according to an embodimentwill be described with reference to accompanying drawings. Termsdescribed below are terms defined in consideration of functions in theembodiments and may vary depending on the intention of a user oroperator or a practice. Therefore, such terms should be defined on thebasis of the entire contents disclosed herein. In addition, thefollowing examples propose rather than limit the scope of the presentinvention, and various embodiments may be implemented through thepresent invention.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to accompanying drawings. Meanwhile,it will be clarified in advance that the term “lighting module orlighting apparatus” as used herein collectively refers to a lightingapparatus used for indoor or outdoor use, such as a flat panel light, aluminaire, a streetlight, various lamps, an electric signboard, aheadlight, or the like.

FIG. 1 is an exploded perspective view of a lighting apparatus accordingto an embodiment, FIG. 2 is an assembled perspective view of thelighting apparatus of FIG. 1, FIG. 3 is a side cross-sectional view ofthe lighting apparatus of FIG. 2, FIG. 4 is a partial enlarged view ofthe lighting apparatus of FIG. 2, FIG. 5 is an exploded perspective viewof a heat dissipation body and a heat dissipation cover of FIG. 1, FIG.6 is an assembled perspective view of the heat dissipation body and theheat dissipation cover of FIG. 5, and FIG. 7 is an enlarged view of afirst back cover of the lighting apparatus of FIG. 3.

Referring to FIGS. 1 to 7, a lighting apparatus 100 includes a housing110 having one or more back covers 111 and 112, recesses 115 and 115A atlower portions of the back covers 111 and 112, a heat dissipation body150 disposed on one side of the lower portion of the one or more backcovers 111 and 112, light emitting modules 170 and 170A disposed on theheat dissipation body 150, and light-transmissive sheets 180 and 180Adisposed in the recesses 115 and 115A under the back covers 111 and 112.

The housing 110 may include back covers 111 and 112 having recesses 115and 115A, which are recessed convexly at a lower portion, and the backcovers 111 and 112 may be disposed in at least one or plural in thehousing 110. The back covers 111 and 112 may be disposed in at least onein the housing 110. In this case, the heat dissipation body 150 and thelight emitting modules 170 and 170A may be disposed on one side of theback covers 111 and 112. For convenience of description, an embodimentwill be described with reference to a housing 110 having a plurality ofback covers 111 and 112. For example, the back covers 111 and 112 mayinclude first and second back covers 111 and 112 symmetrical to eachother with respect to a centerline. Here, the centerline may be astraight line extending from a center of a first axial direction X to asecond axial direction Z at the bottom of the housing 110.

An inside surface of each of the back covers 111 and 112 may include aparabola shape or an ellipse shape. An outer shape of the first andsecond back covers 111 and 112 may include a plurality of parabolashapes, a plurality of ellipse shapes, a hyperbola, or a pair of curvedsurfaces, and the present invention is not limited thereto.

A reflective member may be disposed on at least a part of the insidesurfaces of the back covers 111 and 112. The reflective member mayinclude at least one of reflective sheets 160 and 165. A firstreflective sheet 160 adjacent to the light emitting modules 170 and 170Aof the reflective sheets 160 and 165 and a second reflective sheet 165disposed outside the first reflective sheet 160 may be disposed. Atleast one of the first and second reflective sheets 160 and 165 may notbe formed. For example, the second reflective sheet 165 may not beformed. The first reflective sheet 160 may reflect incident lightspecularly, and the second reflective sheet 165 may reflect incidentlight irregularly. When the back covers 111 and 112 are formed of amaterial that reflects irregularly, the second reflective sheet 165 maybe removed. The first and second reflective sheets 160 and 165 may bedisposed overlapped vertically with the light-transmissive sheets 180and 180A disposed on the recesses 115 and 115A. The first reflectivesheet 160 may have a convex curved surface and the second reflectivesheet 165 or an inside surface may have a convex curved surface.

The first and second back covers 111 and 112 may be linearly symmetricalwith respect to a centerline or the heat dissipation body 150. A powersupply apparatus (not shown) may be provided on the back covers 111 and112, and is not limited thereto.

The recesses 115 and 115A are disposed under each of the first andsecond back covers 111 and 112, respectively. The recesses 115 and 115Aare opened in a downward direction and have opposite sidewalls in thesecond axial direction Z.

As shown in FIG. 3, a length X1 in the first axial direction X and alength in the second axial direction Z may be the same or different inthe back covers 111 and 112. A thickness Y1 or a height of the housing110 or the back covers 111 and 112 may be 1/10 or less of the length X1in the first axial direction X and/or the length in the second axialdirection Z, and may range, for example, from 49 to 59 mm. The thicknessY1 of the back covers 111 and 112 may be disposed in 1/10 or less of thelength in the first axial direction X and/or the second axial directionZ, and thus it is possible to provide a lighting apparatus having a slimthickness. The first axial direction X is a transverse direction or awidth direction of the housing 110, and the second axial direction Z maybe a vertical direction or a longitudinal direction as an axialdirection perpendicular to the first axial direction X. In addition, thethird axial direction Y may be the height direction.

A latching protrusion 113 may be disposed on an outer periphery of thehousing 110, and the latching protrusion 113 may be coupled to anotherstructure, for example, a ceiling. The latching protrusion 113 may bedisposed in a stepped structure from an outer bottom of the housing 110.The latching protrusion 113 may be disposed on an outer periphery of theouter bottom of the housing 110 and may be disposed at higher than thebottom of the housing 110. The latching protrusion 113 may be disposedalong the outer periphery of the housing 110, or may be disposed onopposite outer sides of the housing 110.

The back covers 111 and 112 of the housing 110 may include at least oneof plastic materials such as polycarbonate (PC), polyethyleneterephthalate glycol (PETG), polyethylene (PE), polystyrene paper (PSP),polypropylene (PP), and polyvinyl chloride (PVC).

The back covers 111 and 112 may be a material having a higherreflectance than a transmittance, and material having a reflectance of70% or more, for example, 80% or more. The back covers 111 and 112 mayhave higher reflectance, and thus light incident on surfaces of the backcovers 111 and 112 can be reflected. The back covers 111 and 112 may bea material having a light absorption rate of 20% or less, for example,15% or less, and is not limited thereto. The first and second backcovers 111 and 112 of the housing 110 may be formed of a white material.

As shown in FIG. 3, a fastening hole 105 for fastening to otherstructures may be disposed in the back covers 111 and 112. The fasteninghole 105 may be disposed in an upper portion region of the outer sidesurfaces of the first and second back covers 111 and 112. A regionbetween the first and second back covers 111 and 112 is formed as aconcave connection part 117 which is lower than the outer side surfacesof the first and second back covers 111 and 112, and the connection part117 may be a boundary portion between the first and second back covers111 and 112. The connection part 117 has a thickness greater than thatof a material of the first and second back covers 111 and 112, andsupports a center region of the housing 110. The connection part 117 maybe disposed in a concave region, and thus components such as a powersupply apparatus can be disposed on the connection part 117. The backcovers 111 and 112 have symmetrical shapes, and thus for convenience ofdescription, one back cover will be described as a reference.

The heat dissipation body 150 may be disposed under one side region ofthe back cover 111. The heat dissipation body 150 may be disposed underone region of the first back cover 111. The heat dissipation body 150may be disposed under a center region of the first and second backcovers 111 and 112. The heat dissipation body 150 may be disposed in aregion between the first recess 115 of the first back cover 111 and thesecond recess 115A of the second back cover 112. The heat dissipationbody 150 may be disposed long along the connection part 117 under theconnection part 117 of the housing 110. A groove 117A may be disposed ina lower portion of the connection part 117, and the groove 117A may beformed in an upward concave shape at the lower portion of the connectionpart 117.

The heat dissipation body 150 may be formed of a metal material and mayinclude at least one of metals such as aluminum, copper, nickel, andsilver, and is not limited thereto. The heat dissipation body 150 mayinclude a carbon substance, and is not limited thereto.

A plurality of light emitting modules 170 and 170A may be disposed onthe heat dissipation body 150. The heat dissipation body 150 supportsthe plurality of light emitting modules 170 and 170A and dissipates heatgenerated from the plurality of light emitting modules 170 and 170A. Theheat dissipation body 150 may be disposed between the connection part117 of the housing 110 and a heat dissipation cover 155. The heatdissipation body 150 and the heat dissipation cover 155 may be fastenedto the connection part 117 of the housing 110.

The plurality of light emitting modules 170 and 170A may be located onthe opposite sides of the heat dissipation body 150. The plurality oflight emitting modules 170 and 170A may be disposed inside the recesses115 and 115A at opposite sides. The heat dissipation body 150 may beformed in a symmetrical shape with respect to a centerline, and is notlimited thereto. The centerline may be a line in an axial direction Yperpendicular to a center in the first axial direction X in a lightingapparatus.

As shown in FIGS. 3 to 6, the heat dissipation body 150 includes heatdissipation portions 151 and 151A and reflecting portions 153 and 153A.The heat dissipation portions 151 and 151A have a flat vertical surfaceand may face a predetermined region of the light-transmissive sheets 180and 180A. The heat dissipation portions 151 and 151A may include a firstheat dissipation portion 151 disposed inside the lower portion of thefirst back cover 111 and a second heat dissipation portion 151A disposedinside the lower portion of the second back cover 112. The first heatdissipation portion 151 may be disposed inside the first recess 115, andthe second heat dissipation portion 151A may be disposed inside thesecond recess 115A. Here, the first and second recesses 115 and 115A maybe separated from each other by the heat dissipation body 150. The firstand second heat dissipation portions 151 and 151A may be disposed on theopposite sides of the heat dissipation body 150. The first heatdissipation portion 151 may be disposed parallel to the second heatdissipation portion 151A in the second axial direction Z.

The first and second heat dissipation portions 151 and 151A have flatsurfaces, and the flat surfaces are disposed in a vertical plane such asthe third axial direction Y and disposed at a right angle to the firstaxial direction X. The first and second heat dissipation portions 151and 151A are disposed in opposite directions to each other with respectto a center of a lighting apparatus. The first and second heatdissipation portions 151 and 151A may be arranged in a direction of thedifferent recesses 115 and 115A, for example, in a light emittingdirection.

As shown in FIGS. 3, 4 and 6, light emitting modules 170 and 170A aredisposed on each of the heat dissipation portions 151 and 151A, andcenter side main light in light emitted from the light emitting modules170 and 170A may be radiated to the light-transmissive sheets 180 and180A, which may be defined as direct lighting. Side sub-light in lightemitted from the light emitting modules 170 and 170A may be reflected inthe recesses 115 and 115A and radiated to the light-transmissive sheets180 and 180A, which may be defined as indirect lighting. An embodimentmay include indirect lighting and direct lighting, which may reduce ahot spot by direct lighting through indirect lighting.

Reflecting portions 153 and 153A may be disposed at a lower portion ofthe heat dissipation body 150. The reflecting portions 153 and 153A maybe connected to lower portions of the heat dissipation portions 151 and151A. The reflecting portions 153 and 153A may include a plurality ofreflection regions having different radii of curvature for reflectingincident light. The reflecting portions 153 and 153A include first andsecond reflecting portions 153 and 153A extending from each of the heatdissipation portion 151 and 151A. The first reflecting portion 153 mayextend downward from the first heat dissipation portion 151, and thesecond reflecting portion 153A may extend downward from the second heatdissipation portion 151A.

The first reflecting portion 153 may be disposed between the first heatdissipation portion 151 and the heat dissipation cover 155, and thesecond reflecting portion 153A may be disposed between the second heatdissipation portion 151A and the heat dissipation cover 155. The firstreflecting portion 153 may be disposed under the first light emittingmodule 170, and the second reflecting portion 153A may be disposed underthe second light emitting module 170A. The first and second reflectingportions 153 and 153A may have concavely curved or inclined surfaces.

The first reflecting portion 153 may be disposed between the first heatdissipation portion 151 and a lower end portion of the firstlight-transmissive sheet 180. The second reflecting portion 153A may bedisposed between the second heat dissipation portion 151A and a lowerend portion of the second light-transmissive sheet 180A. An uppersurface of the first reflecting portion 153 may include a reflectionregion having different radii of curvature, and an upper surface of thesecond reflecting portion 153A may include a reflection region havingdifferent radii of curvature.

The first and second reflecting portions 153 and 153A are adjacent tothe light emitting modules 170 and 170A, and reflect second side lightin light emitted from a light emitting diode (LED) 173 to thelight-transmissive sheets 180 and 180A and the inside surfaces of theback covers 111 and 112. A third reflective sheet 162 may be disposed onan inside surface of the reflecting portion 153 or 153A, or thereflecting portion 153 or 153A may be coated with a reflection material,or a metal surface of the heat dissipation body 150 may be exposed.

The third reflective sheet 162 may be disposed on an inside surface ofthe reflecting portion 153 or 153A and reflect light emitted from theLED 173.

Referring to FIGS. 4 to 6, a heat dissipation cover 155 may be disposedunder the heat dissipation body 150. The heat dissipation cover 155 mayinclude a metal material and be combined with the metal body 150, andthus heat dissipation efficiency can be improved. The heat dissipationcover 155 may be in surface contact with the heat dissipation body 150.A part of the heat dissipation cover 155 is in contact with a regionbetween the first and second heat dissipation portions 151 and 151A, andthus conducted heat can be dissipated.

A latching groove 158 may be provided at least one of outside the heatdissipation body 150 and the heat dissipation cover 155, and lower endportions of the light-transmissive sheets 180 and 180A may be disposedin the latching groove 158.

A lower portion plate 156 of the heat dissipation cover 155 extends in adirection of the first and second recesses 115 and 115A. The lowerportion plate 156 may be moved away from the center as getting away fromthe center, with respect to a horizontal straight line from a center.The lower portion plate 146 may have a concave curved or inclinedsurface with a lower center and extend to the lower end portions of thelight-transmissive sheets 180 and 180A coupled to each of the recesses115 and 115A.

As shown in FIG. 6, an upper portion 157 of the heat dissipation cover155 may be inserted into and coupled to a receiving groove 153B of theheat dissipation body 150. The upper portion 157 of the heat dissipationcover 155 has a shape to be inserted into the receiving groove 153B, forexample, a horizontal coupling portion and a vertical supportingportion, the coupling portion is coupled to the receiving groove 153B,and the vertical supporting portion is connected to the heat dissipationplate 156. Here, as shown in FIG. 5, a plurality of fastening holes 153Cmay be disposed inside the receiving groove 153B, and a fastening hole(not shown) corresponding to the hole 153C may be disposed on the upperportion 157 of the heat dissipation cover 155. Accordingly, the upperportion 157 of the heat dissipation cover 155 may be fastened to theheat dissipation body 150 through the fastening holes, and the heatdissipation body 150 may be fixed to the housing 110 by a couplingmember such as a fastening means together with the heat dissipationcover 155. As another example, the heat dissipation cover 155 may beintegrally formed with the heat dissipation body 150, and is not limitedthereto.

Referring to FIG. 6, upper portions 154 and 154A of the heat dissipationbody 150 may be inserted into the groove 117A of the center sideconnection part 117 of the back cover 111 and then fixed with a couplingmember, and the coupling member may include an adhesive, fasteningmeans, or a hook, and is not limited thereto. The fastening means mayinclude components such as a screw or a rivet.

As shown in FIGS. 1 and 6, the light emitting modules 170 and 170A maybe disposed on the heat dissipation portions 151 and 151A of the heatdissipation body 150. The light emitting modules 170 and 170A include afirst light emitting module 170 disposed on the first heat dissipationportion 151 and a second light emitting module 170A disposed on thesecond heat dissipation portion 151A.

Each of the light emitting modules 170 and 170A includes a circuit board171 and a plurality of LEDs 173 disposed on the circuit board 171. Thecircuit board 171 may stand in the third axial direction Y and may bedisposed long in the second axial direction Z, and the plurality of LEDs173 may be arranged in the second axial direction Z on the circuit board171.

The circuit board 171 may be disposed on the heat dissipation portions151 and 151A in a longitudinal direction (Z-axis direction) of the heatdissipation body 150. The circuit board 171 may be disposed in one orplural on the heat dissipation portions 151 and 151A, and is not limitedthereto. The circuit board 171 may be attached to the heat dissipationportions 151 and 151A by screws and/or adhesives, and is not limitedthereto.

The circuit board 171 may include, for example, a printed circuit board(PCB). The PCB includes at least one of a resin material PCB, a metalcore PCB (MCPCB), and a flexible PCB (FPCB), and for example, may beprovided as a metal core PCB for heat dissipation.

The LED 173 may be a package in which a light emitting chip is packagedand emit at least one of blue, red, green, and white lights, and UV. Forexample, white light may be emitted for lighting. The LED 173 may bemounted on the circuit board 171 in a chip form. In this case, the LED173 may have an orientation angle of 115 degrees or more, for example,118 degrees or more. In this case, the orientation angle of the LED 173may vary depending on a structure of a package or a shape of a cavity ina package, and is not limited thereto.

The LED 173 may be arranged on the circuit board 171 in one row or twoor more rows, and is not limited thereto.

According to the embodiment, the LED 173 may include, for example, awarm white LED and a cool white LED on the circuit board 171. The warmwhite LED and the cool white LED are an apparatus emitting white light.The warm white LED and the cool white LED may each emit a correlatedcolor temperature and emit white light of mixed light, and thus thecolor rendering index (CRI) indicating a proximity to the naturalsunlight becomes high. Therefore, it is possible to prevent color of anactual object from being distorted, thereby reducing the fatigue of auser's eyes.

As shown in FIGS. 3 and 4, the light-transmissive sheets 180 and 180Aincludes a first light-transmissive sheet 180 disposed under the firstrecess 115 and a second light-transmissive sheet 180A disposed under thesecond recess 115A. The first light-transmissive sheet 180 and thesecond transmitting sheet 180A are disposed obliquely, and the internalangle formed by the first light-transmissive sheet 180 and the secondlight-transmissive sheet 180A may be less than 180 degrees, for example,170 degrees or less.

The light-transmissive sheets 180 and 180A may be a sheet having adiffusing agent or may include a diffusion sheet material. Thelight-transmissive sheets 180 and 180A may include at least one of adiffusion sheet, for example, at least one of polymethyl methacrylate(PMMA), polypropylene (PP), polyethylene (PE), and polystyrene (PS). Thelight-transmissive sheets 180 and 180A may be caught and fixed to thelatching groove 158 of a lower end portion 152 of the heat dissipationbody 150 and a latching groove 118 of the back covers 111 and 112.

Here, the light-transmissive sheet 180 may be disposed obliquely on therecesses 115 and 115A of the back covers 111 and 112. The latchinggroove 118 may protrude from the inside surfaces of the back covers 111and 112.

An embodiment may remove the reflective sheet on a convex curved surfaceof the inside surfaces of the back covers 111 and 112. As shown in FIG.7, when there is no reflective sheet on the inside surfaces of the backcovers 111 and 112, the inside surfaces of the back covers 111 and 112may be divided into a plurality of reflection regions M1 and M2 disposedbetween the LED 173 and an upper end portion of the light-transmissivesheet 180. The reflection regions M1 and M2 may include a firstreflection region M1 adjacent to the LED 173 and a second reflectionregion M2 disposed between the first reflection region M1 and the upperend portion of the light-transmissive sheet 180.

The first reflection region M1 may reflect first side light L1 fromlight emitted from the LED 173 to the second reflection region M2. Thesecond reflection region M2 may reflect main light radiated from the LED173 and light reflected from the first reflection region M1 to thelight-transmissive sheet 180. The first reflection region M1 may includea plurality of reflective surfaces having different radii of curvatureor inclined surfaces. The second reflection region M2 may include aplurality of reflective surfaces having different radii of curvature orplanes.

The first reflection region M1 is a specular reflecting region, and thesecond reflection region M2 is a scattered reflecting region forincident light L1, L2, and L3. The first reflection region M1 may bedisposed in a region that is deviated from a direction of a quarter oforientation angle (angle A1, A2, and A3 in FIG. 9) with reference to anoptical axis X0 of the LED 173. The first reflection region M1 may forman angle of 28 to 33 degrees with respect to opposite ends of the LED173 and may be wider than an angle formed between opposite ends of thesecond reflection region M2 (A3 in FIG. 9). The second reflection regionM2 may form an angle (A3 in FIG. 9) ranging from 21 to 26 degrees withrespect to the opposite ends of the LED 173 and may be smaller than anangle R1+R2+R3+R4 of FIG. 9 formed by the first reflection region M1.Accordingly, the first reflection region M1 may be disposed in an anglerange that allows the right side light L1 incident thereon to bereflected specularly to different region of the second reflection regionM2.

A straight line perpendicular to a center P of a top surface of the LED173 may be defined as an optical axis X0. The light-transmissive sheet180 has a first point Px intersecting the optical axis X0, and the firstpoint Px may be located at a point equal to or more than ½, for example,⅔ of an upper end of the light-transmissive sheet 180. In addition, asecond point Py may be ⅓ from the upper end of the light-transmissivesheet 180.

The upper end of the light-transmissive sheet 180 and the first point Pxmay have an angle range of less than 10 degrees with respect to the LED173, and is not limited thereto. With respect to the center P of the topsurface of the LED 173, an angle formed by opposite ends of thelight-transmissive sheet 180 is greater than an angle formed by thefirst reflection region M1 or the second reflection region M2, and, forexample, may range from 34 to 39 degrees.

A third reflection region M3 may be disposed on a region other than theback covers 111 and 112, for example, on the heat dissipation body 150or the heat dissipation cover 155. The third reflection region M3reflects the incident light to the second reflection region M2 or thelight-transmissive sheet 180. With respect to the center P of the topsurface of the LED 173, an angle formed by opposite ends of the thirdreflection region M3 on a lower portion may be greater than an angleformed by the first reflection region M1 or the second reflection regionM2.

When the reflective sheets 160 and 165 are disposed on the insidesurfaces of the back covers 111 and 112, referring to FIGS. 3 to 6, thefirst reflective sheet 160 may be disposed on the first reflectionregion M1, and the second reflective sheet 165 may be disposed on thesecond reflection region M2, and the third reflective sheet 162 may bedisposed on the third reflection region M3.

The first reflective sheet 160 may include a material different fromthat of the second reflective sheet 165. The first reflective sheet 160may include a specular reflective sheet or a mirror sheet, and thesecond reflective sheet 165 may include a scattered reflective sheet ora white color sheet. The first reflective sheet 160 may includematerials of Ag or Al. The second reflective sheet 165 may include awhite color plastic material such as polycarbonate (PC), or anano-coated layer, or a pattern-formed metal layer or resin layer. Thethird reflective sheet 162 may include the same material as that of thefirst reflective sheet 160.

The first, second, and third reflective sheets 160, 165, and 162 mayinclude curved surfaces having a plurality of inflection points, and thecurved surfaces may reflect light to a desired optical path.

The first and second reflective sheets 160 and 165 include a materialhaving a light reflectance of 90% or more. In addition, the firstreflective sheet 160 includes a material having a reflectance higherthan that of the second reflective sheet 165. Such a light reflectancemay reflect light without loss of incident light, and thus a lightextraction effect can be improved. The third reflective sheet 162 may beformed of the same material as that of the first reflective sheet 160,for example, a specular reflection material.

Here, at least one of the first and second reflective sheets 160 and 165may be removed, and is not limited thereto. When the heat dissipationbody 150 is a specular reflection material, the third reflective sheet162 may be removed, and is not limited thereto.

Referring to FIG. 7, the light-transmissive sheet 180 may be disposedobliquely. The light-transmissive sheet 180 may be disposed and inclinedat an angle θ1 in the range of 13 degrees or less, for example, 9 to 13degrees, with respect to an optical axis X0. The light-transmissivesheet 180 may be disposed and inclined in the range of, for example, 11to 12 degrees with respect to the optical axis X0. When thelight-transmissive sheet 180 deviates from the angle θ1, a distributionof light reflected from the first to third reflective sheets 160, 165,and 162 may not be uniform. In addition, the light-transmissive sheet180 may directly receive and diffuse main light emitted from the LED 173by the inclined angle θ1.

An upper surface of the LED 173 or a rear surface of the circuit board171 may be disposed at a right angle or in a range of 89 to 91 degreeswith respect to the first horizontal axis X. Accordingly, the lightemitted from the LED 173 may be directly radiated onto entire regionsB1, B2, and B3 of the light-transmissive sheet 180.

When light reflected from the first and third reflective sheets 160 and162 is reflected irregularly by the second reflective sheet 165 and isincident on the different regions B1, B2, and B3, the light-transmissivesheet 180 diffuses and transmits the incident light. Accordingly, it ispossible to prevent the occurrence of a bright line in thelight-transmissive sheet 180 by directly incident light and indirectlyincident light, and to prevent glare.

A minimum distance between a center of the LED 173 and the firstreflective sheet 160 may be in a range of 8 mm or more, for example, 9to 11 mm. When the minimum distance between the center of the LED 173and the first reflective sheet 160 is smaller than the above range,light deviating from the orientation angle may be incident, and thus theimprovement of the reflection efficiency can be insignificant. When theminimum distance between the center of the LED 173 and the firstreflective sheet 160 is greater than the above range, it is difficult tocontrol a path through which light is reflected, and thus leakage ofside light may occur.

A minimum distance between the center of the LED 173 and the thirdreflective sheet 162 may be in a range of 5 mm or less, for example, 4to 4.8 mm. When such a minimum distance is smaller than the above range,the circuit board 171 may not be easily installed. When the minimumdistance is greater than the above range, leakage of side light mayoccur.

A minimum distance between the center of the LED 173 and thelight-transmissive sheet 180 may be at least two times the minimumdistance between the LED and the first reflective sheet, and, forexample, may range from 20 to 23 mm. When the minimum distance betweenthe center of the LED 173 and the light-transmissive sheet 180 isgreater than the above range, inclination becomes too large, and thus itis difficult to uniformly control the light distribution. When theminimum distance between the center of the LED 173 and thelight-transmissive sheet 180 is smaller than the above range, hot spotsor bright lines may be generated.

As shown in FIG. 8, the first reflective sheet 160 includes a largenumber of reflective surfaces S1, S2, S3, and S4, and the large numberof reflective surfaces S1, S2, S3, S4 may include curved surfaces havingpositive radii of curvature. Radii of curvature of the large number ofreflective surfaces S1, S2, S3, and S4 may become greater as a distancefrom the LED 173 increases. The large number of reflective surfaces S1,S2, S3, and S4 may be at least three, and, for example, may includethree to five. When the number of the reflective surfaces S1, S2, S3,and S4 is too small, it is difficult to control dispersion of light, andwhen the number of the reflective surfaces S1, S2, S3, and S4 is toolarge, brightness of the reflected light may be deteriorated.

The large number of reflective surfaces S1, S2, S3, and S4 may include,for example, first through fourth reflective surfaces S1, S2, S3, andS4. The first reflective surface S1 has a radius of curvature in therange of 40 to 50 mm, for example, 44 to 48 mm, the second reflectivesurface S2 has a radius of curvature of at least two times, for example,2.5 to 3 times the radius of curvature of the first reflective surfaceS1, and the third reflective surface S3 may have two times or more theradius of curvature of the second reflective surface S2 and may have 5times or more, for example, 5.6 times to 6.1 times or less the radius ofcurvature of the first reflective surface S1.

The fourth reflective surface S4 may have 1.5 times or more the radiusof curvature of the third reflective surface S3 and may be disposedbetween nine to twelve times the radius of curvature of the firstreflective surface S1. The fourth reflective surface S4 may have aradius of curvature in the range of 450 mm or more, for example, 460 mmto 500 mm. The fourth reflective surface S4 may have the largest radiusof curvature in the first reflective sheet 160 and may reflect theincident light to the second reflective sheet 165.

A straight line distance of opposite ends of the fourth reflectivesurface S4 is greater than that of opposite ends of each of the firstthrough third reflective surfaces S1, S2, S3, and a straight linedistance of opposite ends of the third reflective surface S3 may begreater that of opposite ends of the second reflective surface S2. Astraight line distance of opposite ends of the second reflective surfaceS2 may be greater than that of opposite ends of the first reflectivesurface S1. As a distance from the LED 173 increases, the straight linedistance of opposite ends of each of the reflective surfaces S1, S2, S3,and S4 increases gradually, and thus light may be radiated to each ofregions of the second reflective sheet 165.

Referring to FIGS. 8 and 9, when viewing an angle P formed betweenopposite ends of each of the first to fourth reflective surfaces S1, S2,S3, and S4 of the first reflective sheet 160 and the center of the topsurface of the LED 173, an angle P (R1) of the first reflective surfaceS1 is in the range of 8 to 10 degrees, an angle P (R2) of the secondreflective surface S2 is in the range of 9.5 to 12 degrees, an angle P(R3) of the third reflective surface S3 in the range of 5 to 7.5degrees, an angle P (R4) of the fourth reflective surface S4 is in therange of 3 to 6 degrees.

The third reflective sheet 162 may be disposed between the lower endportion of the light-transmissive sheet 180 and the LED 173. The thirdreflective sheet 162 may include a large number of reflective surfacesS5, S6, S7, and S8 having different radii of curvature. The reflectivesurfaces S5, S6, S7, and S8 of the third reflective sheet 162 may haveradii gradually increased as getting farther away from the LED 173. Forexample, the reflective surfaces S5, S6, S7, and S8 of the thirdreflective sheet 162 may include two or more, for example, three or morecurved surfaces or planes. The reflective surfaces S5, S6, S7, and S8 ofthe third reflective sheet 162 may include fifth through eighthreflective surfaces S5, S6, S7, and S8, and the fifth reflective surfaceS5 may have greater than the radius of curvature of the first reflectivesurface S1 and, for example, may have 1.5 or more times the radius ofcurvature of the first reflective surface S1 in the range of 15 mm to 19mm.

The radius of curvature of the sixth reflective surface S6 may be twotimes greater than that of the fifth reflective surface S5, for example,may be 2.1 to 2.5 times the radius of curvature of the fifth reflectivesurface S5. The seventh reflective surface S7 may have greater than theradius of curvature of the sixth reflective surface S6 and may havegreater than the radius of curvature of the fifth reflective surface S5by 3.7 times or more, for example, 3.9 to 4.3 times. The eighthreflective surface S8 may have greater than the radius of curvature ofthe seventh reflective surface S7, and the eighth reflective surface S8may range from 4.2 to 4.8 times the radius of curvature of the fifthreflective surface S5, for example, 4.4 times to 4.6 times.

The third reflective sheet 162 may include a ninth reflective surface S9having an inclined plane or a radius of curvature as an overlappingregion with a lower end portion of the light-transmissive sheet 180, andlight incident on the ninth reflective surface S9 may be reflectedirregularly by the second reflective sheet 165.

The third reflective sheet 162 may include a tenth reflective surfaceS10 adjacent to the LED 173 rather than the sixth reflective surface S6,and the tenth reflective surface S10 may be a curved surface or a planarsurface and may reflect light deviating from the orientation angle ofthe LED 173.

Referring to FIGS. 8 and 9, when viewing an angle of the triangleconnected at opposite ends of each of the reflective surfaces S5, S6,S7, S8, and S9 of the third reflective sheet 162 and the center P of theLED 173, an angle P (R5) of the fifth reflective surface S5 is a regiondeviated from an orientation angle and may be reflected by the secondreflective sheet 165 with respect to light deviating from theorientation angle.

Angles P (R6, R7, R8, and R9) of the sixth reflective surface S6 to theeighth reflective surface S8 may become smaller as a distance from theLED 173 increases. For example, at an angle P of the sixth reflectivesurface S6 to the eighth reflective surface S8, the angle P (R8) of theeighth reflective surface S8 may be the smallest, and the angle P (R6)of the sixth reflective surface S6 may be the largest.

The angle P (S6) of the sixth reflective surface S6 may be in the rangeof 15.5 to 17.5 degrees, the angle P (S7) of the seventh reflectivesurface S7 may be in the range of 8.5 to 11 degrees, the angle P (S8) ofthe eighth reflective surface S8 may be in the range of 2 to 4 degrees,and the angle P (S9) of the ninth reflective surface S9 may be in therange of 5 to 9 degrees. The fifth to ninth reflective surfaces S5, S6,S7, S8 and S9 are disposed in a parabola shape in a region between theLED 173 and the light-transmissive sheet 180, and reflect the incidentlight to the second reflective sheet 165 and the light-transmissivesheet 180, and thus the light-transmissive sheet 180 may be uniformlyradiated to suppress generation of a bright line due to the lightdirectly radiated. The tenth reflective surface S10 may be disposed in aregion that does not affect light distribution.

Meanwhile, when viewing the angle distribution of each reflective sheetstarting from the LED in FIG. 9, the angles A1 and A2 may be the halfangle of the orientation angle with respect to the optical axis X0 ofthe light emitting diode, the angle A3 may be an angle P with respect toopposite ends of the second reflective sheet 165, and the angle A4 maybe an angle P with respect to opposite ends of the light-transmissivesheet 180. The angles A1 and A2 range from 62 to 65 degrees, the angleA3 ranges from 22 to 26 degrees, and the angle A4 ranges from 33 to 36degrees. Here, the orientation angle may be 115 degrees or more, forexample, 118 degrees or more, and the half angle of the orientationangle may be 57.5 or more, for example, 58 degrees or more.

As shown in FIG. 10, the fourth reflective surface S4 of the firstreflective sheet 160 reflects light incident from the LED 173 to a firstregion E1 of the second reflective sheet 165, and light incident on thefirst region E1 may be reflected irregularly and radiated to a firstpoint Px of the light-transmissive sheet 180 and a peripheral regionthereof, for example, a center lower portion region. The first region E1may be a region adjacent to the first reflective sheet 160, and may be aregion of 0 to 25% from an interface with the first reflective sheet 160in the region of the second reflective sheet 165.

As shown in FIG. 11, the third reflective surface S3 of the firstreflective sheet 160 reflects the light incident from the LED 173 to asecond region E2 of the second reflective sheet 165, and the lightincident on the second region E2 may be reflected irregularly andradiated to a center of the light-transmissive sheet 180 and aperipheral region thereof. The second region E2 may be a region rangingfrom 25 to 40% from the interface with the first reflective sheet 160.

As shown in FIG. 12, the second reflective surface S2 of the firstreflective sheet 160 reflects the light incident from the LED 173 to athird region E3 of the second reflective sheet 165, the light incidenton the third region E3 may be reflected irregularly and radiated to thecenter and the peripheral region B2 of the light-transmissive sheet 180.The third region E3 may be a region ranging from 40% to 55% from theinterface with the first reflective sheet 160.

As shown in FIG. 13, the first reflective surface S1 of the firstreflective sheet 160 reflects the light incident from the LED 173 to afourth region E4 of the second reflective sheet 165, and the lightincident on the fourth region E4 may be reflected irregularly andradiated to the center and the peripheral region B2 of thelight-transmissive sheet 180. The fourth region E4 may be a regionranging from 40 to 55% from the interface with the first reflectivesheet 160. Here, the first and second reflective surfaces S1 and S2 ofthe first reflective sheet 160 reflect specularly the incident light andradiates in a range of 40 to 55% from a specific region of the secondreflective sheet 165, for example, a boundary with the first reflectivesheet 160, and radiates to a center region B2 of the light-transmissivesheet 180. Accordingly, the bright line by the main light directlyradiated from the LED 173 in the center region B2 of thelight-transmissive sheet 180 may be reduced by the indirectly incidentlight.

Referring to FIG. 14, the fifth reflective surface S5 of the thirdreflective sheet 162 reflects the light incident from the LED 173 to thefifth region E5 of the second reflective sheet 165, and the lightincident on the fifth region E5 is reflected irregularly and radiated toan upper portion edge region B1 of the light-transmissive sheet 180adjacent to the second reflective sheet 165. The fifth region E5 may bea region ranging from 85 to 100% from the interface with the firstreflective sheet 160.

Referring to FIG. 15, the sixth reflective surface S6 of the thirdreflective sheet 162 reflects the light incident from the LED 173 toupper portion regions B1 and B2 of the light-transmissive sheet 180. Theupper portion region of the light-transmissive sheet 180 may range from50 to 100% from a lower end of the light-transmissive sheet 180.

Referring to FIG. 16, the seventh reflective surface S7 of the thirdreflective sheet 162 reflects the light incident from the LED 173 to thesixth region E6 of the second reflective sheet 165, and the lightreflected irregularly from the sixth region E6 may be radiated in arange of 30 to 40% of the light-transmissive sheet 180.

According to an embodiment, the second reflective sheet 165 reflectsirregularly the light incident from the first reflective sheet 160 andthe LED 173 and uniformly irradiates the center region B2 of thelight-transmissive sheet 180, and thus it is possible to suppress thegeneration of a bright line due to the light directly incident on thelight-transmissive sheet 180 from the LED 173. The light reflected bythe third reflective sheet 162 is reflected irregularly by the secondreflective sheet 165 or radiated onto the upper portion regions B1 andB2 of the light-transmissive sheet 180, and thus it is possible toeliminate a bright line caused by light directly incident on thelight-transmissive sheet 180 from the LED 173.

The first to third reflective sheets 160, 165 and 162 improve uniformityof distribution of the light directly radiated to the light-transmissivesheet 180 by the LED 173, thereby eliminating a bright line of a lightincident portion. It can be seen from the light flux distribution of thelight-transmissive sheet of the lighting apparatus that the bright lineis eliminated. Here, a size of the lighting apparatus is 550 to 600mm×550 to 600 mm, and a thickness or height ranges from 50 to 52 mm. Theorientation angle of the LED may also be in the range of 120 degrees+/−5%.

When viewing the Unified Glare Rating (UGR) of the lighting apparatus ofthe present invention, the UGR is 19 or less, indicating that the usermay not have uncomfortable glare. In the CIE regulations, it isclassified that a user has a discomfort glare when the UGR is 21 ormore.

Table 1 illustrates UGR, light efficiency, and light uniformity of thelighting apparatus according to an embodiment.

TABLE 1 UGR Endwise (horizontal) Crosswise (vertical) Light EfficiencyUniformity 18.2 19.0 85.1% 82.2%

<Light Emitting Device Package>

FIG. 17 is a sectional view showing a light emitting diode according tothe embodiment.

Referring to FIG. 17, the light emitting diode 200 includes a body 210;first and second lead electrodes 211 and 213, at least portions of whichare disposed in the body 210, a light-emitting device 101 electricallyconnected to the first and second lead electrodes 211 and 212 on thebody 210, and a molding member 220 surrounding the light emitting device101.

The body 210 may be formed of at least one of a silicon material, asynthetic resin material and a metallic material. The body 210 mayinclude a cavity formed therein and a reflective portion 215 having aninclined surface at the periphery thereof.

The first lead electrode 211 and the second lead electrode 213 areelectrically separated from each other, and are formed to pass throughthe body 210. That is, the inner side portions of the first and secondlead electrodes 211 and 212 may be disposed in the cavity and the otherportions of the first and second lead electrodes 211 and 212 may bedisposed at an outside of the body 210.

The first lead electrode 211 and the second lead electrode 212 providepower to the light-emitting device 100 Also, the first lead electrode211 and the second lead electrode 213 reflect the light emitted from thelight emitting device 101, thus improving the light emitting efficiency.Also, the first lead electrode 211 and the second lead electrode 213 mayserve to discharge the heat generated from the light emitting device101.

The light emitting device 101 may be disposed on the body 210, or may beformed on the first lead electrode 211 and/or the second lead electrode212. The light emitting device 101 may be arranged as at least one LED(Light Emitting Diode) chip. The LED chip may include a light emittingdiode in a visible light band such as red, green, blue or white, or a UVlight emitting diode that emits ultraviolet (UV) light. A phosphor layermay be further disposed on the surface of the light emitting device 101,but the present invention is not limited thereto.

The wire 216 of the light emitting device 101 may be electricallyconnected to at least one of the first and second lead electrodes 211and 212, but the embodiment is not limited thereto.

The molding member 220 may surround the light-emitting device 101 toprotect the light emitting device 101. Also, the molding member 220 mayinclude a fluorescent material to change the wavelength of light emittedfrom the light emitting device 101. The upper surface of the moldingmember 220 may be flat, concave or convex. The upper surface of themolding member 220 or the cavity region may be the light emittingsurface according to the embodiment, but the present invention is notlimited thereto.

A lens may be disposed on the molding member 220, but the presentinvention is not limited thereto.

The light emitting diode 200 may be a blue light emitting device or awhite light emitting device having a high color rendering index (CRI).The light emitting diode may be a light emitting device that emits whitelight by molding a synthetic resin containing a phosphor on a blue lightemitting chip. The phosphor may include at least one of a garnet (YAG,TAG), a silicate, a nitride, and an oxy-nitride.

The features, structures, effects and the like described in theembodiments are included in at least one embodiment of the presentinvention, and are not necessarily limited to only one embodiment.Furthermore, the features, structures, effects and the like illustratedin the embodiments can be combined and modified by other persons skilledin the art to which the embodiments belong. Therefore, it is to beunderstood that the present invention is not limited to theseembodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

INDUSTRIAL APPLICABILITY

An embodiment may be applied to a flat panel lighting apparatus.

An embodiment may be applied to a lighting apparatus for a flat panelhaving a light emitting diode.

1. A lighting apparatus, comprising: a housing having a first back coverincluding a recess at lower portion and a reflective surface of aparabolic shape; a first light emitting module disposed on a firstcorner of the recess of the back cover and having a plurality of lightemitting diodes (LEDs) arranged in a first direction; and alight-transmissive sheet disposed in an oblique direction at a recess ofthe housing and transmitting light emitted from the light emittingdiode, wherein the reflective surface includes a first reflection regionadjacent to the LEDs and a second reflection region disposed between anupper portion of the light-transmissive sheet and the first reflectionregion, wherein the first reflection region reflects light incident fromthe LEDs to a different region of the second reflection region, whereinthe second reflection region reflects irregular light incident from thefirst reflection region to a center region of the light-transmissivesheet, wherein the light-transmissive sheet includes a lower regionwhich is disposed at a lower position than a horizontal straight linewith respect to the plurality of LEDs and an upper region which isdisposed at a higher position than the horizontal straight line.
 2. Thelighting apparatus of claim 1, comprising: a third reflection regiondisposed between the LEDs and a lower end portion of thelight-transmissive sheet, wherein the third reflection region has aconcave curved surface, and the third reflection region reflectsspecularly the incident light to the light-transmissive sheet and thesecond reflection region.
 3. The lighting apparatus of claim 2, whereinthe first reflection region and the third reflection region include ametal material and the second reflection region includes a non-metallicmaterial.
 4. The lighting apparatus of claim 1, comprising: a heatdissipation body in which the light emitting module is disposed, andwherein the heat dissipation body is disposed on the first corner of therecess.
 5. The lighting apparatus of claim 3, wherein the thirdreflection area is disposed on the heat dissipation body.
 6. A lightingapparatus, comprising: a housing including first and second back coversdisposed on opposite sides of a center and each having an inside surfacein a parabola shape; an recess opened at lower portions of the first andsecond back covers; a first light-transmissive sheet disposed in anoblique direction in a recess of the first back cover; a secondlight-transmissive sheet disposed in an oblique direction in a recess ofthe second back cover; a first light emitting module having a pluralityof LEDs arranged in a first direction at a first corner of the recess ofthe first back cover; a second light emitting module having a pluralityof LEDs arranged in the first direction at a second corner of the recessof the second back cover; a heat dissipation body in which the first andsecond light emitting modules are disposed in a region between therecess of the first back cover and the recess of the second back cover;and a first reflective sheet disposed adjacent to the LEDs in the insidesurfaces of the first and second back covers, and reflecting first sidelight emitted from the plurality of LEDs, wherein the heat dissipationbody includes a first heat dissipation portion in which the first lightemitting module is disposed, a second heat dissipation portion in whichthe second light emitting module is disposed, a first reflecting portiondisposed between the first heat dissipation portion and a lower end ofthe first light-transmissive sheet, and a second reflecting portiondisposed between the second heat dissipation portion and a lower end ofthe second light-transmissive sheet, wherein the first reflective sheethas a plurality of reflective surface, wherein the firstlight-transmissive sheet includes a lower region which is disposed at alower position than a first horizontal straight line with respect to theLEDs of the first light emitting module and an upper region which isdisposed at a higher position than the first horizontal straight line,and wherein the second light-transmissive sheet includes a lower regionwhich is disposed at a lower position than a second horizontal straightline with respect to the LEDs of the second light emitting module and anupper region which is disposed at a higher position than the secondhorizontal straight line.
 7. The lighting apparatus of claim 6, whereinthe first and second back covers have a shape linearly symmetrical withrespect to a centerline, forms the inside surfaces of the first andsecond back covers into a convex curved surface, and includes a secondreflective sheet disposed on the inside surfaces of the first and secondback covers, wherein the second reflective sheet is disposed between thefirst reflective sheet and an upper end portion of the first and secondlight-transmissive sheets, respectively, and the second reflective sheetreflects the light reflected from the plurality of LEDs and the firstreflective sheet to the first and second light-transmissive sheets. 8.The lighting apparatus of claim 7, wherein the first and secondreflecting portions of the heat dissipation body have concavely curvedor inclined surfaces, and include a third reflective sheet having alarge number of reflective surfaces having different radii of curvatureon the surfaces of the first and second reflecting portions.
 9. Thelighting apparatus of claim 8, wherein the third reflective sheetreflects specularly the light incident from the plurality of LEDs to anupper region of the second reflective sheet and an upper region of thefirst and second light-transmissive sheets.
 10. The lighting apparatusof claim 6, wherein the first and second light-transmissive sheetsinclude a diffusion sheet.
 11. The lighting apparatus of claim 7,wherein the first reflective sheet includes a specular reflectionmaterial, and wherein the first and second light-transmissive sheetsincludes a diffusion sheet.
 12. The lighting apparatus of claim 11,wherein the second reflective sheet includes a scattered reflectionmaterial.
 13. The lighting apparatus of claim 6, wherein the reflectivesurfaces of the first reflective sheet have different radii ofcurvature, and radii of curvature of the reflective surfaces of thefirst reflective sheet gradually increase as getting far away from acenter of a top surface of the LEDs.
 14. The lighting apparatus of claim8, wherein a radius of curvature of the reflective surface of the thirdreflective sheet gradually increases as getting farther away from acenter of a top surface of the LEDs.
 15. The lighting apparatus of claim8, wherein the third reflective sheet is disposed closer to the LEDsthan the first reflective sheet.
 16. The lighting apparatus of claim 6,wherein the first and second light emitting modules include a circuitboard on which the LEDs are disposed, the circuit board of the first andsecond light emitting modules is disposed on the first and second heatdissipation portions, the first and second heat dissipation portionshave a perpendicular surface, and the circuit board of the first andsecond light emitting modules is disposed in parallel, and wherein thefirst and second dissipation portions are disposed on opposite sides ofthe center of the housing.
 17. The lighting apparatus of claim 6,comprising: a heat dissipation cover disposed below the heat dissipationbody, wherein the heat dissipation cover includes a lower portion platedisposed under lower end portions of the first and secondlight-transmissive sheets.
 18. The lighting apparatus of claim 17,wherein the lower portion plate of the heat dissipation cover isdisposed and inclined from a lower portion center of the heatdissipation cover.
 19. The lighting apparatus of claim 18, wherein thelower end portions of the first and second light-transmissive sheets aredisposed between the first and second reflecting portions of the heatdissipation body and the lower portion plate of the heat dissipationcover.
 20. The lighting apparatus of claim 18, wherein an LED of theplurality of LEDs includes a body having a cavity, a light emitting chipdisposed in the cavity of the body, and a molding member having aphosphor disposed in the cavity, and an angle formed by the first andsecond light-transmissive sheets with respect to an optical axis of theLED is 13 degrees or less.